Curved lenses and related methods

ABSTRACT

Curved lenses and methods for making curved lenses are described. One embodiment of a method of making a curved lens includes curving a lens blank made of a linear polarizer layer laminated together with a plurality of polymeric layers. The lens blank is curved by heating and pressing the lens blank between a curved rigid member and a flexible member at a pressure and maintaining the pressure for a time sufficient to allow the lens blank to conform to the shape of the curved rigid member. Methods of the invention may be used to make curved lenses with different polarization properties and curvatures.

CROSS-REFERENCE TO RELATED APPLICATION

The application claims priority to U.S. Provisional Application Ser. No.61/475,885 titled “Apparatus and Method for Shaping Light Polarizers,”which was filed on Apr. 15, 2011 and is incorporated herein by referencein its entirety.

FIELD OF THE INVENTION

The invention relates to the field of polarized eyewear, and, moreparticularly, to curved polarized lenses and eyewear having curvedpolarized lenses.

BACKGROUND

Light polarizing lenses such as those incorporated into sunglasses orother eyewear are preferably shaped to comply with fashion trends, tominimize the amount of light that can disturb the wearer's peripheralvision and to minimize the appearance of reflections. Unfortunately,there are currently very few techniques that can transform planarpolarizing lens blank materials into a curved lens. The techniques thatexist may suffer from one or more of the following drawbacks: some canproduce only very thin lenses, the lens production process is notadapted for efficient automation, they may involve time consuminggrinding processes, or the forming process may damage the linearpolarizer.

SUMMARY

In view of the foregoing, it is an object of the invention to providecurved polarizer lenses, which can be produced according to efficientlyautomated processes that impart minimal damage to the delicate linearpolarizer material.

According to a method aspect of the invention, a formed lens is preparedfrom a lens blank made of a linear polarizer layer laminated togetherwith a plurality of polymeric layers, the linear polarizer layer havinga polarization axis. Heat and pressure are applied to the lens blank bypressing the lens blank between a curved rigid member and a flexiblemember, thereby causing the flexible member to assume the shape of thecurved rigid member. The pressure is maintained for a time sufficient toallow the lens blank to conform to the shape of the curved rigid memberand the flexible member.

In another method aspect of the invention, a formed lens is preparedfrom a lens blank made of a linear polarizer layer laminated togetherwith a plurality of polymeric layers, the linear polarizer layer havinga polarization axis. The lens blank is heated to a forming temperatureby pressing the lens blank between a curved rigid member and a flexiblemember, the curved rigid member being at the forming temperature. Thepressure is maintained while heating at the forming temperature forallowing the lens blank to conform to the shape of the curved rigidmember. The temperature is reduced to a reduced temperature whilemaintaining the pressure for allowing the lens blank to become a rigidlens having a convex side and a concave side. The rigid lens is thenremoved from between the curved rigid member and the flexible member.

In another method aspect of the invention, eyewear is prepared from afirst lens and a second lens made of a linear polarizer layer laminatedtogether with a plurality of polymeric layers, the linear polarizerlayer having a polarization axis. The first lens and second lens areformed from lens blanks into a desired shape according to the followingsteps: (i) heating and pressing the lens blanks separately between acurved rigid member and a flexible member at a pressure, thereby causingthe flexible member to assume the shape of the curved rigid member, (ii)maintaining the pressure for a time sufficient to allow the lens blanksto conform to the shape of the curved rigid member and the flexiblemember. The formed first and second lenses are then placed into aneyeglass frame.

The following are preferred forming parameters that may optionally beused in methods of the invention. Heating is preferably conducted atabout 70° C. to about 200° C. The pressure is about 1.5 to about 15 MPa.

In some embodiments, a method may comprise cooling the lens blank whilemaintaining the pressure. Cooling may be conducted at about 20° C. toabout 90° C.

In some embodiments, a method may comprise, heating the lens blank to atemperature of between about 20° C. to about 150° C. prior to placingthe lens blank between the curved rigid member and flexible member andpressing the lens blank.

In certain embodiments, at least one of the polymeric layers is anoptical wave retarder having fast and slow axes and the fast retarderaxis is aligned at an angle relative to the polarizer axis. The anglemay be chosen to render the lens a linear polarizer, an ellipticalpolarizer, or a circular polarizer.

In embodiments in which the lens is a circular polarizer, ananti-reflective coating may be applied to the concave surface and convexsurface of the formed lens. This advantageously allows the formed lensto have a parallel polarizer transmittance equal to or greater than 90%and a cross polarizer transmittance equal to or less than 0.5%.

In some embodiments, the shape of the curved rigid member may beadjusted to produce a spherically, toroidally, or cylindrically shapedlens. A spherically shaped lens has a first radius of curvature and asecond radius of curvature perpendicular to the first radius ofcurvature, wherein the first radius of curvature and second radius ofcurvature are equal. A toroidally shaped lens has a first radius ofcurvature and a second radius of curvature perpendicular to the firstradius of curvature, wherein the first radius of curvature and secondradius of curvature are not equal. A cylindrically shaped lens has afirst radius of curvature and a second radius of curvature perpendicularto the first radius of curvature, wherein the first radius of curvatureis non-zero and second radius of curvature is about zero.

Embodiments of the invention also include eyeglass lenses made accordingto method aspects of the invention.

These and other objects, aspects, and advantages of the presentinvention will be better appreciated in view of the drawings andfollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a preferred composite light polarizersheet that can be used to form a lens in accordance with an embodimentof the invention;

FIG. 2 is a side elevation view of another preferred composite lightpolarizer sheet that can be used to form a lens in accordance with anembodiment of the invention;

FIG. 3 is a side elevation view of another preferred composite lightpolarizer sheet that can be used to form a lens in accordance with anembodiment of the invention;

FIG. 4. is a plan view of a preferred composite light polarizer sheetfrom which a lens blank can be cut, showing the alignment of thetransmission axis of the linear polarizer layer and the fast axis of theretarder layer;

FIG. 5 is a plan view of a section of a composite light polarizer sheet,showing how lens blanks may be cut therefrom;

FIG. 6 is a plan view of a lens blank removed from the section ofcomposite light polarizer sheet of FIG. 4.

FIG. 7 is a cross-sectional view of an apparatus that can be used tocurve lens blanks into lenses according to a method aspect of theinvention;

FIG. 8 is a cross-sectional view of the apparatus of FIG. 7 during apressure stage of a method aspect of the invention;

FIG. 9 is a cross-sectional view of the apparatus of FIG. 7, showing acurved lens removed from the apparatus;

FIGS. 10A-C are schematics of spherically, toroidally, and cylindricallyshaped lenses, respectively, made according to a method aspect of theinvention;

FIG. 11 is a perspective view of eyeglasses incorporating lenses of theinvention;

FIG. 12 is a cutaway view of a curved lens including a hard coating inaccordance with an embodiment of the invention; and

FIG. 13 is a cutaway view of a curved lens including an anti-reflectivecoating in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the Summary above and in the Detailed Description of PreferredEmbodiments, reference is made to particular features (including methodsteps) of the invention. It is to be understood that the disclosure ofthe invention in this specification includes all possible combinationsof such particular features. For example, where a particular feature isdisclosed in the context of a particular aspect or embodiment of theinvention, that feature can also be used, to the extent possible, incombination with and/or in the context of other particular aspects andembodiments of the invention, and in the invention generally.

The term “comprises” is used herein to mean that other features, steps,etc. are optionally present. When reference is made herein to a methodcomprising two or more defined steps, the steps can be carried in anyorder or simultaneously (except where the context excludes thatpossibility), and the method can include one or more steps which arecarried out before any of the defined steps, between two of the definedsteps, or after all of the defined steps (except where the contextexcludes that possibility).

This invention may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein.

It is desirable for curved devices that include a light-polarizing layerand that are suitable for application in the manufacture of eyewear tohave durability and abrasion resistance appropriate for the applicationfor which they will be used. It is also desirable that they bemanufacturable by a method adapted efficiently to automated productionoperations. Ideally, such devices should not lose any of theirlight-polarizing qualities during the manufacturing process.

A conventional process for shaping light polarizing lenses usesinjection molding. It will be appreciated that injection moldingoperations are complicated and relatively slow insofar as productionoperations are concerned. Achieving a desired lens curvature byresorting to methods based upon in-mold polymerization or grinding ofeach lens individually will likewise be slow and costly.

The production of curved light-polarizing lenses can be accomplished byindividually shaping (molding) blanks made of a plastic light-polarizingcomposite or structure, such as is shown in U.S. Pat. No. 3,560,076 toF. G. Ceppi. However, such a method is difficult to implement due to thecomplex geometry of the mating molds.

As will be described below, the invention described here overcomes thesedrawbacks. The inventors have advantageously developed thick and durablecurved lenses with minimal or no damage to the linear polarizer materialusing a unique forming process involving curving the lens blanks in asimple and cost efficient manner.

FIGS. 1-3 illustrate exemplary composite light polarizer sheets fromwhich the curved polarized lenses of the invention may be formed.Referring initially to FIG. 1, an exemplary sheet 1 includes a polarizerlayer 12 laminated between first and second polymeric layers 14, 16. Aprotective hardcoat layer 5 is coated on top of both polymeric layers14, 16. Referring to FIG. 2 another exemplary sheet 10 includes apolarizer layer 12 laminated between first and second polymeric layers14,16 and a retarder layer 18 laminated to the second polymeric layer16. Referring now to FIG. 3, an alternative example of a sheet 20includes a polarizer layer 12 laminated to a first polymeric layer 14 onone side and to a retarder layer 18 on the other side. A secondpolymeric layer 16 is laminated to the retarder layer 18 on the side ofthe retarder layer 18 that is opposite the polarizer layer 12.

The polarizer layer 12 is preferably a linear polarizer, which may bemade of any number of suitable linear polarizer materials such as H-typeor K-type polarizers. In a preferred example, the polarizer material ismade from a linear molecularly oriented dichroic light-polarizingmaterial. Such materials typically have a thickness in the range ofabout 0.025 to 0.076 mm. A preferred material to serve as the lightpolarizer is a layer of stretched (oriented) polyvinyl alcohol of about0.025 mm thickness, which is stained with a dichroic dye such as iodine.Optionally, the polarizer may be borated to improve stability.Polarizers of this type are disclosed in U.S. Reissue Pat. Re. 23,297and in U.S. Pat. No. 4,166,871.

Alternatively, the polarizer material may be a stretched polyvinylalcohol (PVA) sheet containing polyvinylene light-polarizing speciessuch as may be provided by typical hydrochloric acid vapor processing.Preferably, such polarizing material will be borated for improvedstability. Suitable light-polarizing materials of this type can beprepared according to U.S. Pat. No. 2,445,555. Other light polarizingmaterials such as those described in U.S. Pat. Nos. 2,237,567;2,527,400; and 2,554,850 may also be used. Regardless of the type ofpolarizer material used, the polarizer material may be sandwiched to orbetween one or more support layers, such as a polymeric material layer14, 16 to provide mechanical strength to the polarizer layer 12.

The polymeric layers 14, 16 are preferably made from one or morethermoplastic polymers, which are polymers that can be formed to adesired shape by applying temperature and/or pressure. Suitable polymersinclude, but are not limited to, cellulose derivatives such as celluloseacetate, cellulose diacetate, cellulose triacetate, or cellulose acetatebutyrate; acrylate derivatives such as polymethylmethacrylate (PMMA);polycarbonates; polyamides, polyurethanes; polypropylenes;polyethylenes; or cyclo-olefin based polymers or copolymers. Thepolymeric material layers 14,16 may be made from a single layer of asingle polymer, a single layer of a blend of polymers, multiplelaminated layers of a single polymer, or multiple laminated layers madeof different polymers or a blend of polymers.

It is preferred that the polymeric layers 14, 16 provide durability,mechanical strength, and scratch resistance to the sheet 12 and thefinished curved lens made from the sheet 12. In some cases, it may bebeneficial to use polymers that either carry or may be provided with asuitable protective coating such a polymeric hard coating 5 that canwithstand the temperatures and pressures used in the forming process.Suitable protective coatings include polyurethanes, polyacrylates, orurea-based resins.

The retarder layer 18 is preferably made from a light transmissivebirefringent material such as a cyclo-olefin based polymer orco-polymer. Other suitable materials that can be used to form theretarder layer 18 include, but are not limited to, acrylate basedpolymer, polypropylenes, polyesters, cellulose acetate based polymers,PVA, polystyrenes, polycarbonates, and norbornene based polymers andco-polymers.

One or more additives may be included in the polarizer layer 12,polymeric layers 14, 16 and/or retarder layer 18. For example,stabilizers, UV absorbers, and colorant dyes may be employed dependingon the desired properties of the finished curved optical filter.

The polarizer layer 12 and retarder layer 18 include axes that may bealigned relative to one another to produce a desired polarizationeffect. Referring to FIG. 4, an exemplary sheet 30 having polarizerlayer 12 and a retarder layer 18 is shown. The polarizer layer 12 has atransmission axis T aligned at the angle θ. The fast axis R of theretarder layer 18, is aligned at the angle φ=θ+β where β is the angularoffset of the fast axis R of the retarder layer 18 relative to thetransmission axis T of the polarizer layer 12. When β=(n−1) (π/2) with nan integer, the two axes are either parallel or orthogonal to each otherand the sheet 30 behaves as a linear polarizer. When β=(2n−1) (π/4) withn an integer, the sheet 30 behaves as a circular polarizer. For anyother values of β, the sheet 30 behaves as an elliptical polarizer.

In more detail, the linear polarizer layer 12 has a transmission axis Toriented at θ and defined by the Stoke vector of Eq. (1).

$\begin{matrix}{\frac{1}{2}{\begin{pmatrix}{S_{0} + {{S_{1} \cdot \cos}\; 2\theta} + {{S_{2} \cdot \sin}\; 2\;\theta}} \\{{{S_{0} \cdot \cos}\; 2\theta} + {{S_{1} \cdot \cos^{2}}2\;\theta} + {{S_{2} \cdot \sin}\; 2{\theta cos}\; 2\;\theta}} \\{{{S_{0} \cdot \sin}\; 2\;\theta} + {{S_{1} \cdot \sin}\; 2\;{\theta cos}\; 2\;\theta} + {{S_{2} \cdot \sin^{2}}2\;\theta}} \\S_{3}\end{pmatrix}.}} & {{Eq}.\mspace{14mu}(1)}\end{matrix}$The polarizer comprises a linear polarizer layer 12 with transmissionaxis T orientated at θ and a retarder layer with its fast axis R alignedat φ defined by the Stoke vector of Equation 2.

$\begin{matrix}{{\frac{1}{2}\begin{pmatrix}{S_{0} + {\cos\; 2\;{\theta \cdot \left( {{S_{1}\cos^{2}2\;\phi} + {S_{2}\cos\; 2\;{\phi sin}\; 2\;\phi} - {S_{3}\sin\; 2\;\phi}} \right)}} + \;{\sin\; 2{\theta \cdot \left( {{S_{1}\cos\; 2\;{\phi sin}\; 2\;\phi} + {S_{2}\sin^{2}2\;\phi} + {S_{3}\cos\; 2\;\phi}} \right)}}} \\{{\cos\; 2\;{\theta \cdot S_{0}}} + {\cos^{2}2\;{\theta \cdot \left( {{S_{1}\cos^{2}2\phi} + {S_{2}\cos\; 2{\phi sin2}\;\phi} - {S_{3}\sin\; 2\phi}} \right)}} + {\sin\; 2\;{\theta cos}\; 2\;{\theta \cdot \begin{pmatrix}{{S_{1}\cos\; 2\;{\phi sin}\; 2\phi} +} \\{{S_{2}\sin^{2}2\;\phi} + {S_{3}\cos\; 2\phi}}\end{pmatrix}}}} \\{{\sin\; 2\;{\theta \cdot \; S_{0}}} + {\sin\; 2{\theta cos}\; 2\;{\theta \cdot \left( {{S_{1}\cos^{2}2\;\phi} + {S_{2}\cos\; 2{\phi sin}\; 2\;\phi} - {S_{3}\sin\; 2\phi}} \right)}} + {\sin^{2}2{\theta \cdot \begin{pmatrix}{{S_{1}\cos\; 2{\phi sin}\; 2\;\phi} +} \\{{S_{2}\sin^{2}2\;\phi} + {S_{3}\cos\; 2\;\phi}}\end{pmatrix}}}} \\{{S_{1}\sin\; 2\phi} - {S_{2}\cos\; 2\;\phi}}\end{pmatrix}S} = {\begin{pmatrix}S_{0} \\S_{1} \\S_{2} \\S_{3}\end{pmatrix}.}} & {{Eq}.\mspace{14mu}(2)}\end{matrix}$defines the Stoke vector of light that is transmitted though the sheet30.

Using these relationships any number of sheets 1, 10, 20, 30configurations can be formed depending on the desired polarizationproperties of the sheet 1, 10, 20, 30 and the finished curved lens. Inpractice one may form a sheet 10, 20, 30 having desired polarizationproperties by predetermining the desired polarization properties of thesheet 10, 20, 30 and then forming the sheet 10, 20, 30 in such a waythat the fast axis R of the retarder layer 18 is aligned at the desiredangle relative to the polarization axis T of the polarizer layer 12 toachieve the desired polarization properties.

In preparation for making a curved lens, lens blanks may be prepared bycutting and removing blanks of a size and shape suited for theproduction of the desired lens from a composite light polarizer sheet ofthe invention. A preferred method of preparing a blank to be formed intoa lens is shown in FIG. 4, which is a plan view of a section of sheet 40from which blanks 42, 44 are cut and removed. The blanks 42, 44 areprepared by making a cut 46 through the section of sheet 40. The cut 46defines the perimeter of an individual blank 42, 44 from which a blank48 can be removed as shown in FIG. 5. Suitable methods of making the cut46 include the use of a rolling knife cutter, a reciprocal stampingcutter, a straight edge cutting knife, a rotary die, or a laser cutter.

Individual blanks, such as blank 48 shown in FIG. 5, may be formed intolenses in the manner described below. In certain embodiments, the blanks48 may be subjected to one or more pre-forming treatments such ascleaning, coating, or polishing if desired.

A method by which a blank 48 of the invention is formed into a lens thatis concave on one side and convex on the other side will now bedescribed in connection with FIGS. 7 through 9.

The forming process can be carried out by an apparatus 50 of the typeshown in FIG. 7. The apparatus includes a flexible member support 52, acurved rigid member 54, a mechanism for driving the curved rigid member54 into and out of pressure-applying relationship with the flexiblemember support 52, and mechanism for alternately heating and cooling thecurved rigid member 54 during each pressure-applying interval.

The flexible member support 52 includes a fixed support 60 with theflexible member 56 attached thereto.

The curved rigid member 54 includes a metal member 68, a shaft 72operatively connected to a suitable drive mechanism, a fluid chamber 74,a fluid inlet coupling 76, and a fluid outlet coupling 78. The metalmember 68 has a smooth solid convex forming surface 70.

The use of the metal member 68 is advantageous over conventional lenspress molds such as glass molds. Due to their fragility and complexity,glass molds only allow for spherical lenses to be formed. Moreover,glass molds would not be able to withstand the higher pressures neededto form some of today's thicker and tougher curved lenses, such as thelenses of the invention. Further, metal members 68 with different shapesmay be interchanged to match a desired lens curvature. Therefore, ratherthan just being able to form spherically curved lenses, as one wouldwith the conventional glass molds, the invention allows for toroidallyor cylindrically shaped lenses to be formed simply by selecting asuitably shaped metal member 68.

A preferred drive mechanism includes a suitable hydraulic piston andcylinder arrangement 80 operatively connected to the curved rigid member54 for moving the curved rigid member 54 into and out ofpressure-applying relationship with the flexible member support 52.

A preferred heating and cooling mechanism for the curved rigid member 54includes a three-way valve 82, a heating fluid conduit 84, a coolingfluid conduit 86, and fluid inlet 88 connecting the three way valve 82to the fluid inlet coupling 76.

In forming a curved lens, a blank 48 is placed on the flexible member56. The flexible member 56 and the convex forming surface 70 are thenmoved into contact with the blank 48 as shown in FIG. 8. As pressure isapplied to the blank 48, the flexible member 56 deforms and assumes theshape of the convex forming surface 70.

With the application of heat and pressure, the convex forming surface 70and the deformed flexible member 56 curve the blank 48 into a shapedlens characterized by concave and convex opposed surfaces.

The amount of pressure applied and the pressure profile may be adjusteddepending on the characteristics of the blank 48, with the temperaturesof the forming surface 70 and with the curvature intended to be given tothe blank 48.

In a preferred embodiment, the pressure applied to the blank 48 is inthe range of about 1.50 to about 15 MPa.

During the pressure application stage, the curved rigid member 54 isheated by passing hot fluid through the fluid chamber 74. The formingsurface 70 is continually heated at a temperature sufficient to causedeformation of the lens blank 48 material and conformation of thesurfaces of blank 48 to the forming surface 70. Application of pressureby the curved rigid member 54 onto the blank 48 therebetween causes theblank 48 to deform between the curved rigid member 54 and the flexiblemember 56 producing a curved polarizer.

In a preferred embodiment the flexible member 56 has a thickness betweenabout 0.5 mm and about 5.0 mm, shore hardness A between about 25 andabout 70, a tensile strength between about 5 MPa and about 30 MPa, anelongation at break between about 100% and about 1000%, and a resistanceto tearing between about 50 N/cm to about 1000 N/cm.

In some embodiments, it may also be desirable to utilize a curved rigidmember 54 having a forming surface 70 corresponding to a predeterminedcurvature of the convex side of the lens to be formed. The convexsurface of the lens, formed against the flexible member 56, may serve asthe outer surface of an eyeglass lens. A suitable radius of curvaturefor the forming surface 70 is about 50 to about 270 mm, or about 65 toabout 90 mm. In a particular embodiment, the forming surface 70 iscylindrically shaped and has a radius of curvature of about 52.3 mm.

The temperature sufficient to cause the blank 48 to deform may vary withthe chemical composition of the blank's 48 composite structure. Apreferred heating temperature range is between about 70° C. to about200° C. Another preferred heating range is between about 90° C. to about110° C. One particular preferred heating temperature is about 105° C.

In some cases it may be helpful to pre-heat the blank 48 before applyingpressure. Suitable pre-heating temperatures are within the range ofabout 20° C. to about 150° C.

The temperature of the forming surface 70 of the curved rigid member 54can be controlled by the passage of heated fluid and cooled fluid, asdescribed previously. The curved rigid member 54 is preferablypreheated, prior to placement of the blank therebetween, to the desiredforming temperature for a heating cycle sufficient to provide thedesired shaped lens. The desired forming temperature is maintained for aduration sufficient to effect desired lens formation. Although notlimiting, a suitable duration is between about 80 to about 90 seconds.Thereafter, the temperature of the forming surface 70 is reduced bypassing a cooling fluid, through the fluid chamber 74 of the curvedrigid member 54. The cooling fluid is passed through the curved rigidmember 54 for a time sufficient to cool the formed lens. Although notlimiting, a suitable cooling duration is about 30 seconds. Coolingtemperatures from about 20° C. to about 35° C. provide good results, butother cooling temperatures are also contemplated.

Hot fluid is supplied to the curved rigid member 54 through the heatingfluid conduit 84 and the relatively cool fluid is supplied through thecooling fluid conduit 86. During the heating cycle, the valve 82 opens aconnecting passage between the heating fluid conduit 84 and the inlet 76and closes the cooling fluid conduit 86. During the cooling cycle, thevalve 82 opens a connecting passage between the cooling fluid conduits86 and the inlet 76 and closes the heating fluid conduit 84. Thetransition from the heating cycle to the cooling cycle is carried out byoperating the valve 82 to mix cool fluid with the hot fluid until thehot fluid is completely displaced by cool fluid. Transition from thecooling cycle to heating cycle is carried out by reversing theoperation.

After the cooling operation, the flexible member support 52 and thecurved rigid member, 54 are separated to relieve the pressure on theformed lens 90 and permit its removal, as shown in FIG. 9. If the formedlens 90 adheres to one of the members 52, 54, it may be removed byapplying a stream of compressed air.

One or more coatings can be applied on the concave and/or convexsurfaces of the formed lens 90 using conventional vacuum depositiontechniques. The inventors discovered that applying an anti-reflectivecoating to the convex and concave surfaces of a circular polarizer lensof the invention can significantly improve the transmittance % of thefinished circular polarizer lens.

The method described above can also include repeating each of thesesteps using a series of curved rigid members 54 for the shaping ofblanks 48 to each of a series of solid convex lens surfaces, each ofsuch surfaces having a different curvature within a desired range ofcurvatures, thus providing a series of lenses, each having a differentsolid convex surface within a desired range of curvatures.

A lens of the invention may also gradually be shaped to a desired formby repeating the steps and gradually increasing the curvature of thecurved rigid member 54 prior to each repetition. This can beaccomplished using a series of curved rigid members 54 with each set inthe series having an increased curvature relative to the prior set.

The shape of a formed lens of the invention will substantiallycorrespond to the shape of the forming surface 70. Accordingly,different shaped forming surface 70 can be used to form lenses withdifferent curvatures. For example, a pair of spherically shaped, a pairof cylindrically shaped, or a pair of toroidally shaped forming surface70 can be used to form spherically curved, cylindrically curved, andtoroidally curved light polarizer lenses, respectively.

For spherically, toroidally, and cylindrically curved lenses, the shapeof the lens, along the first principal meridian correspondssubstantially to the relationship r1=(n−1)/D1, the shape of the lensalong the second principal meridian, perpendicular to the firstprincipal meridian, corresponds substantially to the relationshipr2=(n−1)/D2, n represents the index of refraction of the blank 48, D1and D2 are the intended lens curvatures, r1 and r2 are the radii ofcurvature of each principal meridian of the solid convex forming surface70. In preferred embodiments, r1 and r2 are typically in the range ofabout 1 to about 10 diopters To form a spherically curved lens r1 equalsr2. To form a toroidally curved lens r1 is different from r2. To form acylindrically curved lens, r1 is different from r2 and r2 is about 0diopter. The lens thickness is typically in the range of about 0.2 mm toabout 2.5 mm. This relationship can also apply to other shapedcurvatures.

FIGS. 10A-C depict a formed spherical lens 90′, a formed toroidal lens90″, and a formed cylindrical lens 90′″, respectively. The curvature ofeach lens 90′, 90″, 90′″ is characterized by a first radius of curvaturer1 and a second radius of curvature r2. The lines along which r1 and r2are determined are indicated. For the spherically curved lens 90′, r1equals r2. For the toroidally curved lens 90″, r1 is different from r2.For the cylindrically curved lens 90′″, r1 is different from r2 and r2is about 0 diopter.

Another object of the invention is to provide polarized eyewear thatincludes two lenses of the invention. Referring to FIG. 11, the eyewear100 includes an eyeglass frame 102, a first lens 104 and a second lens106. The lenses 104, 106 may be the same or different, depending on thedesired use of the eyewear. For the manufacture of linear polarizedeyewear, the first lens 104 and second lens 106 are preferablyidentical. The sheet used for these lenses will have a stoke vector asdescribed in Equation 1 with the polarizer axis orientated parallel tothe horizontal (θ=0). In some preferred examples for stereoscopic use,both lenses are made of linear polarizer sheet having a stoke vector asdescribed in Equation 1 with the polarizer axis of the first lens 104oriented at θ and the polarizer axis of the second lens 106 oriented atθ+π/2. In a further preferred example for stereoscopic use, the sheetmaterial comprises a retarder layer 18 and has a Stoke vector asdescribed in Equation 2. The first lens 104 has its polarizer axis Torientated at θ and fast axis of the retarder R orientated at φ=θ+β andthe second lens 106 has its polarizer axis T orientated at θ and fastaxis of the retarder R orientated at φ=θ−β.

EXAMPLES

In this section, certain illustrative embodiments of the invention aredescribed. These are provided by way of example only and, therefore, donot limit the scope of the invention.

Example 1 Preparation of a Lens of the Invention

A spherically shaped linear polarizer lens of the invention was preparedusing the method and apparatus described above. The structure of thelens 112 will be better understood by referring to FIG. 12. The lens 112was formed from a total of six layers of material including a polarizerlayer 12, a first polymeric layer 14, a second polymeric layer 16, athird polymeric layer 118, a first hard coat layer 114 and a second hardcoat layer 116. The lens has its maximum thickness in the centralportion. The materials used to make the lens 112, the properties of theplatens, and the forming parameters are all specified in TABLE 1.

TABLE 1 Materials and Parameters Used to Form an Exemplary Lens of theInvention Lens Materials Layer 1 (114) hardcoat Layer 2 (118) cellulosetriacetate Layer 3 (16) cellulose triacetate Layer 4 (12) stretched PVAwith iodine Layer 5 (14) cellulose triacetate Layer 6 (116) hardcoatThickness of    0.6 mm blank material Platens Material Curved steelrigid member 54 flexible elastomer member 56 Radius r1   52.3 mm r2   0.0 mm Forming Temperatures pre-heating  50-70° C. Parameters heating90-100° C. cooling  20-35° C. Pressure    5-7 MPa

Example 2 Improvement of Transmittance Using Anti-Reflective Coatings onCircular Polarized Lenses

Circular polarizer lenses of the invention were coated on both the solidconvex and flexible concave surfaces with an anti-reflective coating inorder to determine whether an anti-reflective coating can improve thetransmittance % within the wavelength range of 280 to 700 nm, whichincludes the visible light spectrum. The structure of a circularpolarized lens including an antireflective coating will be betterunderstood with reference to FIG. 13 in which the lens 120 includes apolarizer layer 12, a first polymeric layer 14, a second polymeric layer16, a retarder layer 18, a first antireflective coating layer 122 and asecond antireflective coating layer 124.

TABLE 2 shows results of typical transmittance % improvement.

TABLE 2 Transmittance Improvement Data Anti-reflective coating Crosspolarizer Parallel polarizer applied? transmittance (%) transmittance(%) NO 0.02 82 YES 0.03 90

The application of an anti-reflective coating is used regularly ineyewear products. For both sunglass and corrective eyewear it is appliedto the back of the lens to minimize disturbing back reflections on thelens from light sources situated behind the wearer. For correctiveeyewear, it is also applied at the front of the lens for cosmeticreasons, namely in order to prevent reflections from the front of thelenses, making the eyewear less noticeable.

We found that when anti-reflective coatings are applied to stereoscopiceyewear as described in this example, the coating advantageously andsignificantly increases the transmittance of the light the lens isdesigned to transmit without increasing the transmittance of the lightthe lens is designed to block. In this case, the lenses were designed tomaximize the parallel polarizer transmittance, while minimizing thecross-polarizer transmittance. The results show that the anti-reflectivecoating allowed us to increase by the parallel polarizer transmittanceby 8% with minimal increase in the cross-polarizer transmittance. Thisis especially important to 3D projection operators, such as cinemaoperators, since a significant amount of light is lost in the 3Ddisplay. The ability of the eyewear to transmit more light allows theoperators to use less powerful light sources resulting in significantoperational cost savings.

The present invention has been described hereinabove with reference tothe accompanying drawings, in which preferred embodiments of theinvention are shown. Unless otherwise defined, all technical andscientific terms used herein are intended to have the same meaning ascommonly understood in the art to which this invention pertains and atthe time of its filing. Although various methods and materials similaror equivalent to those described herein can be used in the practice ortesting of the present invention, suitable methods and materials aredescribed. The skilled should understand that the methods and materialsused and described are examples and may not be the only ones suitablefor use in the invention.

Accordingly, this invention may be embodied in many different forms andshould not be construed as limited to the illustrated embodiments setforth herein. The invention has been described in some detail, but itwill be apparent that various modifications and changes can be madewithin the spirit and scope of the invention as described in theforegoing specification and as defined in the appended claims.

That which is claimed is:
 1. A method of making a formed lens, themethod comprising: obtaining a lens blank comprising, in superposedrelation, a linear polarizer layer laminated together with a pluralityof polymeric layers, the linear polarizer layer having a polarizationaxis; placing a lens blank on a flat flexible member of elastomer, theflat flexible member contacting an entirety of, and supporting, the lensblank, wherein the lens blank and the flat flexible member are eachinitially and essentially planar, and wherein the flat flexible memberof elastomer has: a thickness between about 0.5 mm and about 5.0 mm; ashore hardness A between about 25 and about 70; a tensile strengthbetween about 5 MPa and about 30 MPa; an elongation at break betweenabout 100% and about 1000%; and a resistance to tearing between about 50N/cm to about 1000 N/cm; heating and applying a pressure to the lensblank by pressing the lens blank between a curved rigid member and theflat flexible member, causing the flat flexible member to assume a shapeof the curved rigid member while supporting the lens blank therebetween;and maintaining the pressure for a time sufficient to allow the lensblank to conform to the shape of the curved rigid member and the flatflexible member.
 2. The method of claim 1, wherein heating is conductedat about 70° C. to about 200° C.
 3. The method of claim 1, wherein thepressure is about 1.5 MPa to about 15 MPa.
 4. The method of claim 1,further comprising cooling the lens blank while maintaining thepressure.
 5. The method of claim 4, wherein cooling is conducted atabout 20° C. to about 90° C.
 6. The method of claim 1, furthercomprising, preheating the lens blank to a temperature of about 20° C.to about 150° C. prior to applying the pressure.
 7. The method of claim1, wherein at least one of the polymeric layers is an optical waveretarder having a fast axis and the fast axis is aligned at an anglerelative to the polarizer axis.
 8. The method of claim 7, wherein theangle renders the lens a linear polarizer.
 9. The method of claim 7,wherein the angle renders the lens an elliptical polarizer.
 10. Themethod of claim 7, wherein the angle renders the lens a circularpolarizer.
 11. The method of claim 10, further comprising coating aconcave surface and a convex surface of the formed lens with ananti-reflective coating.
 12. The method of claim 11, wherein the formedlens has a parallel polarizer transmittance equal to or greater than 90%and a cross polarizer transmittance equal to or less than 0.5%.
 13. Themethod of claim 1, wherein the shape of the curved rigid member producesa spherically shaped lens having a first radius of curvature and asecond radius of curvature perpendicular to the first radius ofcurvature, wherein the first radius of curvature and second radius ofcurvature are equal.
 14. The method of claim 1, wherein the shape of thecurved rigid member produces a toroidally shaped lens having a firstradius of curvature and a second radius of curvature perpendicular tothe first radius of curvature, wherein the first radius of curvature andsecond radius curvature are not equal.
 15. The method of claim 1,wherein the shape of the curved rigid member produces a cylindricallyshaped lens having a first radius of curvature and a second radius ofcurvature perpendicular to the first radius of curvature, wherein thefirst radius of curvature is non-zero and the second radius of curvatureis zero.
 16. A method of making a formed lens, the method comprising:obtaining a flexible lens blank comprising, in superposed relation, alinear polarizer layer laminated together with a plurality of polymericlayers, the linear polarizer layer having a polarization axis; placingthe flexible lens blank on a flexible member of elastomer, the flexiblemember contacting an entirety of, and supporting, the flexible lensblank, wherein the flexible lens blank and the flexible member are eachinitially and essentially planar, and wherein the flexible member ofelastomer has: a thickness between about 0.5 mm and about 5.0 mm; ashore hardness A between about 25 and about 70; a tensile strengthbetween about 5 MPa and about 30 MPa; an elongation at break betweenabout 100% and about 1000%; and a resistance to tearing between about 50N/cm to about 1000 N/cm; heating the flexible lens blank to a formingtemperature by pressing the flexible lens blank at a pressure between acurved rigid member and the flexible member, while the flexible membersupports the flexible lens blank, the curved rigid member being at theforming temperature; maintaining the pressure while heating at theforming temperature for allowing the flexible lens blank to assume ashape of the curved rigid member; reducing the temperature to a reducedtemperature while maintaining the pressure for allowing the flexiblelens blank to maintain a convex side and a concave side once thepressure is removed; and removing the flexible lens blank from betweenthe curved rigid member and the flexible member.
 17. The method of claim16, wherein the forming temperature is about 70° C. to about 200° C. 18.The method of claim 16, wherein the pressure is about 1.5 MPa to about15 MPa.
 19. The method of claim 16, wherein the reduced temperature isabout 20° C. to about 90° C.
 20. The method of claim 16, furthercomprising, preheating the lens blank to a temperature of about 20° C.to about 150° C. prior to applying the pressure.
 21. The method of claim16, wherein at least one of the polymeric layers is an optical waveretarder having a fast axis and the fast axis is aligned at an anglerelative to the polarizer axis.
 22. The method of claim 21, wherein theangle renders the lens a liner polarizer.
 23. The method of claim 21,wherein the angle renders the lens an elliptical polarizer.
 24. Themethod of claim 21, wherein the angle renders the lens a circularpolarizer.
 25. The method of claim 24, further comprising coating aconcave surface and a convex surface of the formed lens with ananti-reflective coating.
 26. The method of claim 25, wherein the formedlens has a parallel polarizer transmittance equal to or greater than 90%and a cross polarizer transmittance equal to or less than 0.5%.
 27. Themethod of claim 16, wherein the shape of the curved rigid memberproduces a spherically shaped lens having a first radius of curvatureand a second radius of curvature perpendicular to the first radius ofcurvature, wherein the first radius of curvature and second radiuscurvature are equal.
 28. The method of claim 16, wherein the shape ofthe curved rigid member and flexible member produce a toroidally shapedlens having a first radius of curvature and a second radius of curvatureperpendicular to the first radius of curvature, wherein the first radiusof curvature and second radius of curvature are not equal.
 29. Themethod of claim 16, wherein the shape of the curved rigid member andflexible member produced a cylindrically shaped lens having a firstradius of curvature and a second radius of curvature perpendicular tothe first radius of curvature, wherein the first radius of curvature isnon-zero and the second radius of curvature is zero.
 30. A method ofmaking eyewear, the method comprising: obtaining a first lens and asecond lens, the first lens and the second lens comprising, insuperposed relation, a linear polarizer layer laminated together with aplurality of polymeric layers, the linear polarizer layer having apolarization axis, the first lens and the second lens being formed fromlens blanks into a desired shape according to the following steps:placing a lens blank on a flexible member of elastomer, the flexiblemember contacting an entirety of, and supporting, the lens blank,wherein the lens blank and the flexible member are each initially andessentially planar; and wherein the flexible member of elastomer has: athickness between about 0.5 mm and about 5.0 mm; a shore hardness Abetween about 25 and about 70; a tensile strength between about 5 MPaand about 30 MPa; an elongation at break between about 100% and about1000%; and a resistance to tearing between about 50 N/cm to about 1000N/cm; heating and applying a pressure to the lens blank separately bypressing the lens blanks between a curved rigid member and the flexiblemember, while the flexible member supports the lens blank, causing theflexible member to assume a shape of the curved rigid member;maintaining the pressure for a time sufficient to allow the lens blankto conform to the shape of the curved rigid member and the flexiblemember, the curved rigid member responsible for a force to form aconcave side of the lens blank and the flexible member responsible for aresponsive force to form a convex side of the lens blank; and placingthe first lens and the second lens into an eyeglass frame.